Implementation of spin-orbit coupling in a Slater determinant basis with applications to spin-dependent properties.

Abstract

A new program, Eidolon, has been written and optimised so that it can take the CI coefficients from an in-house CASSCF Slater determinant program and the molecular orbital coefficients from Gaussian 09 to calculate the spin-orbit splitting and magnetic g tensor for molecules and spin states. The code can handle interactions between different spin states. A semi-empirical effective nuclear charge was used to form the one-electron spin-orbit operator. Comparison with configuration-state-function based calculations from the Orca package validated the spin-orbit splittings and g tensors obtained from a test set of small molecules, while comparison with experimental values has shown good correspondence. Accuracy is competitive with published results. Eidolon was then exploited to perform calculations using a pruned determinant list,generated by limiting the number of replacements in the list of alpha and beta orbitals, the 'strings', and taking the product of these strings, called 'S-' and 'SD-strings' for single and double substitution respectively. These calculations generated results that were comparable to reported values, provided that significant spin-contamination was allowed. The use of this smaller set of determinants opens up the possibility of performing calculations on significantly larger molecules and manifolds of spin states, such as actinide complexes and molecular magnets.

Date of Award	1 Aug 2018
Original language	English
Awarding Institution	The University of Manchester
Supervisor	McDouall (Supervisor) & Burton (Supervisor)